PROJECT SUMMARY Skeletal muscle contractile function, as characterized by its ability to generate force, is an important determinant of functional independence, chronic disease risk and mortality. Thus, understanding the regulation of muscle force generation is important for the development of strategies to optimize muscle function and quality of life. The long-term objective of this research is to elucidate the new mechanisms that regulate skeletal muscle excitation-contraction coupling, contractile function and, ultimately, its capacity to generate force. In cardiac muscle, phosphorylation-based signaling of contractile proteins is an important regulator of force output. In skeletal muscle, however, its overall contribution to function is minimal, with hitherto unknown modes of regulation proposed as being critical. The fundamental premise of this application is that lysine acetylation of contraction-related proteins is necessary for the ability of skeletal muscle to produce force. Accordingly, in this application our primary objective is to elucidate the importance of the acetyltransferases (KATs), p300 (E1A binding protein p300) and CBP (cAMP response element-binding protein binding protein), to skeletal muscle force generating capacity, and to identify the impact of contraction on the acetylation of contraction-associated proteins, and determine whether that are regulated by p300 and CBP. Our central hypothesis is that acetylation of contraction-related proteins by p300 or CBP (due to functional redundancy) is required for skeletal muscle force generation. To address our hypothesis, we will measure skeletal muscle contractile function in novel mouse models in which p300 and CBP KAT activity is temporally and specifically manipulated in skeletal muscle. Moreover, we will use pharmacological inhibitors of p300/CBP to distinguish the acute and `direct' effects of p300 and CBP on the acetylation of proteins central to muscle function, from the `indirect' effects that occur via regulation of gene transcription. Specifically, Aim #1 will investigate the acute and chronic contributions of p300 and CBP to skeletal muscle force generating capacity, whilst Aim #2 will define the contraction- and p300/CBP-dependent acetylome and phosphoproteome in skeletal muscle. Altogether, these studies will provide insight into the contribution of p300, CBP and acetylation to skeletal muscle contractile function, which we expect will foster the development of novel therapies to improve the force generating capacity of skeletal muscle. Ultimately, the impact to human health would be improvements in functional independence and quality of life for individuals afflicted by disease(s) that impinge muscle function.